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            <p>  看到这个<a href="https://www.cool3c.com/article/158691">新闻</a>，想到公司居然无意中有了进入殡葬行业的潜力，纯属意外。只是同事们去客户支持的时候估计会非常的为难。</p>
<blockquote>
<p>   “X 工，明天你去哪儿出差？”<br>   “呜呜，Y墓地”“<br>   “哈哈，是啥bug呀？”<br>   “客户的客户拜错了先人！客户被打的很惨！令人惊悚的是，据说这个issue是seldom的，我得要去debug了，你说我难不难呀！求你跟我一起去，好不？壮个胆儿？”<br>   “别呀！我可不想去挨打！”</p>
</blockquote>
<p><img src="https://wnnwoo.oss-cn-chengdu.aliyuncs.com/BluetoothCemetery/bluetooth-cemetery-1.png" alt><br>这个极其富有新意的产品，共享墓地，是由日本千叶县的八千代墓园推出的。一块墓地可以放35个骨灰盒，这在地少人多的日本来说，是个很可贵的创意。共享墓地通过一块带有显示屏以及蓝牙模块的墓碑来达到共享的目的，目前相对便宜的价格应该是最大的卖点。一块普通墓地的价格是<a href="https://japantoday.com/category/features/lifestyle/Bluetooth-tombstones-help-you-mourn-loved-ones-without-breaking-the-bank">700万日元</a>，而共享之后是每位29万日元，略大于700万/35=20万。那些担不起昂贵墓地的家庭，就可以考虑选择这样的共享墓地作为家人的长眠之地。具体如何共享的呢？<br>重点在这块屏幕上，屏幕可以根据来访人的身份识别信息变换显示内容。当家属或亲友来致意时，需要带上一个事先在墓园注册过的特殊的护身符（“蓝牙御守”）。当这个护身符靠近墓碑时，墓碑上的蓝牙模块捕获到这个身份识别信息就提前将相对应的作古之人的相关信息显示出来，信息可以是文字，也可以是图片，不拘泥于形式。更为重要的是，这块屏幕上的信息是可定制的，墓园可以从另外一个角度来满足客户需求，增加营收，而跳出目前仅仅拘泥于收取管理费这一种形式。<br> <img src="https://wnnwoo.oss-cn-chengdu.aliyuncs.com/BluetoothCemetery/bluetooth-cemetery-2.png" alt><br>想象下使用到的蓝牙技术也应该比较简单。蓝牙御守做BLE广播，广播自己的ID号，保险起见，ID号千万要加密。蓝牙墓碑做搜索，搜索到ID后，就去匹配保存在数据库里的相关信息，再刷到屏幕上。</p>
<ul>
<li>蓝牙御守可以做到非常便宜。<br>里面放一颗只支持BLE的蓝牙芯片，配一颗纽扣电池，用个3到5年绝对不成问题，广播的频率可以做到非常低，毕竟一年也做不了几次扫墓。想更进一步省电的话，也可以放一颗重力感应传感器，只在感知到移动的时候开蓝牙广播。</li>
<li>共享墓碑的成本可能就要高些了。<br>一块很大的屏幕是刚需，如果要普通墓碑那么大，那就更贵了。一定得配一个MCU来驱动屏幕，如果要更具有扩展行性的话，可以配个好点的带图形加速器的MCU以显示更炫一点的画面。这个应用场景上蓝牙的功能就比较单一了，能稳定的扫描广播数据就行，一般的蓝牙模组就够用。当然也可以配个蓝牙和wifi共存的模块，将来可以从远端支持客户对屏幕显示信息的定制，不用经常跑到墓碑这里来更新数据库。墓碑可以根据客户需求在不同时间显示不同的内容。这样想起来，如果人们的接受度能慢慢起来的话，各种需求就会慢慢的进来，还是可以做不少事情。<br>同样地，独立墓地的墓碑也可以做到定制。假如作古之人在世的时候是个CS高手，那可以把背景定制成他生前喜欢玩的任何一个区的场景；假如他喜欢爬山，那可以把背景定义成攀登者的圣地珠穆朗玛峰；如果喜欢《三体》，可以定制个半人马星座放在背景，等等。</li>
</ul>
<p>这个市场总的容量目前应该非常非常的小，毕竟一般家庭也不愿意家人在去世后还要跟别人挤在一块墓地，如果你去过墓园的话，你会看到即使是独立墓地也是很拥挤的。而且一般墓园也不愿意劳这个神去为这么少的客户去做这个事。不过也许随着老龄化的发展，墓地的价格最后一定会变得越来越高，大家对这个也许慢慢能接受了。</p>

          
        
      
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            <p>《海边的卡夫卡》有一段关于男人和女人的来源的描述，挺新颖有趣，也许可以让某些人对某些无法理解的现象有个释怀的理由。</p>
<blockquote>
<p>按柏拉图《盛宴》中阿里斯托芬的说法，远古神话世界里有三种人。“古时候，世界不是由男和女，而是由男男、男女和女女构成。就是说，一个人用了今天两个人的材料。大家对此心满意足，相安无事的生活。岂料，神用利刀将所有人一劈两半，劈的利利索索。结果，世上只有男和女，为了寻找本应有的另一半，人们开始左顾右盼，慌慌不可终日。”<br>“神为什么做那样的事情呢？”<br>“把人一劈两半？这—，为什么我也不知道。神干的事情基本上都让人琢磨不透。动不动就发脾气，又有时过于—怎么说呢—理想主义的倾向。若容我想象，大概类似某种惩罚吧，就像《圣经》上亚当和夏娃被赶出伊甸园。”<br>“原罪”我问问.</p>
</blockquote>
<p>出于好奇，想了解下神为什么这么做，我在wikipidea上找到了这篇《盛宴》，<a href="https://en.wikipedia.org/wiki/Symposium_%28Plato%29">Symposium（Plato)</a>，Aristophanes有讲到是因为当时这三种人太强大了，威胁到了上帝，所以神（宙斯）就把他们一劈两半，这样他们就整日忙着寻找另外一半，没空想其它的。</p>
<p><img src="https://wnnwoo.oss-cn-chengdu.aliyuncs.com/ManAndWomen/men-women.png" alt></p>

          
        
      
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            <p>我们每个人都有两个世界：好的世界和坏的世界</p>
<blockquote>
<p>好的世界里有父母兄弟姐妹，有爱，有温馨的家；<br>坏的世界里有坏蛋，有打架，有凶杀；</p>
</blockquote>
<p>我们从儿时(childhood)到成人(adulthood)，需要不断游走于这两个世界，学会接受他们的存在，人格才不至于分裂。</p>
<p>单纯的好孩子辛克莱小时候为了合群，在大坏蛋克罗默前面装成熟，撒了个谎，结果被克罗默抓了把柄，以至于相当长一段时间里他一直受克罗默的控制。更重要的是他并没有向父母求助，而是自己一直在默默忍受，而他的两个世界之间的鸿沟越来越大，越来越难走，他性情大变，暴躁易怒，家人都只能小心翼翼的跟他相处，直到他的引路人德米安的出现。 德米安不知道怎么帮他搞定了克罗默，而且德米安向他传输了要接受这两个世界的观念，从此以后他不一样了，踏上了寻找自我的道路。</p>
<blockquote>
<p>对每个人而言，真正的职责只有一个：找到自我。无论他的归宿是诗人还是疯子，是先知还是罪犯——这些其实和他无关，毫不重要。他的职责只是找到自己的命运—-而不是他人的命运——然后在心中坚守其一生，全心全意，永不停息。所有其他的路都是不完整的，是人的逃避方式，是对大众理想的懦弱回归，是随波逐流，是对内心的恐惧。</p>
<p>在童年的枯萎和死亡中，我们爱恋的一切都将离去，身边只剩下世道的孤独和淡漠。很多人在这一关口便举足不前，终其一生痛苦地缅怀无可挽回的往日，缅怀遗失的天堂梦—这正是所有梦幻中最可怕最重要的幻想。</p>
<p>所有人都在寻找共同点，所有人都在拉帮结社，推卸命运的责任，躲进温暖的人群。</p>
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            <p>麦基的《故事》很多地方真是令人叹为观止，这不仅仅是一本教人写故事，写剧本的书，完全是一部关于人生哲理的书，值得常常翻翻。哪些电影里传递的感知，原来我都没接收到过。</p>
<ul>
<li>两种著名的苦难渊源：事业和爱情。</li>
<li>一个人所能享受的欢乐和他愿意承受的痛苦，是成正比的。</li>
<li>人物的性格真相在人处于压力之下做出选择时得以揭示—压力越大，揭示越深，其选择便越真实地体现了人物的本性。</li>
<li>天才就像肌肉一样：如果没有阻力，它就会萎缩。</li>
<li>无论自觉还是不自觉，所有的故事，无论真诚还是虚假，明智还是愚蠢，都会忠实地映现出作者本人，暴露出其人性———或是人性的缺失。</li>
<li>芸芸纵生都过着一种默默绝望的生活。</li>
<li>人物欲望的价值尺度与他为达成欲望而愿意承担的风险成正比；价值越大，风险越大。</li>
<li>就像一个电荷从磁铁的一极跳向另一极，生活的火花也是在自我和现实之间这道鸿沟的两岸来回跳跃。</li>
<li>谁现表白，谁先吃亏。</li>
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            <p>蓝牙一直以来的卖点都是低功耗，不过低功耗的代价是传输距离短，大概也就是30米的样子。为了增加蓝牙通信距离，SIG一直在努力：</p>
<ul>
<li>推出 Coded PHY，在编码中加入更多的冗余数据，接收方可以尽可能的恢复数据，TI测试出来的距离有大概1.5KM。</li>
<li>推出BLE Mesh，原理是让各个蓝牙节点可以通过广播来接力传输数据，达到长距离传输的目的。而要想接力传输，各个节点就不得不既要扫描又要发送数据包，这又丧失了BLE的立身之本，所以在Mesh的规范里又对mesh网络的拓扑结构做了很多规定以节约功耗，如下图，感兴趣的同学可以翻翻<a href="https://www.bluetooth.com/specifications/mesh-specifications/">Spec</a>。<br><img src="https://wnnwoo.oss-cn-chengdu.aliyuncs.com/BluetoothLongRange/MeshTop.png" alt></li>
<li>还有6LOWPAN，让蓝牙数据从L2CAP层接到IP，借助以太网或是wifi来增加传输距离。</li>
</ul>
<p>厂家的思路就有点开阔了：</p>
<ul>
<li><p><a href="https://www.thetileapp.com">Tile</a>这个公司是做防丢追踪器的。比如买个防丢设备挂到钥匙圈上，你就可以通过手机app去找倒钥匙圈。还有一家智能耳机厂商Skullcandy原生就支持这个app，可以直接通过手机找耳机，不需要再在耳机上挂个防丢器。不过Tile做的比较有创意的地方是该公司运营了一个社区。假如你的设备丢了，你可以在手机app上启动“社区寻找”的功能，让所有支持社区搜寻的手机帮你找设备，借助社区的力量结局了距离的问题。比如你出差的时候，耳机丢在了美国的酒店，你回国后在家里触发这个社区搜寻的功能，而酒店有服务员的手机支持社区搜寻的功能而且搜到了你的耳机，那你就能看到自己的耳机在这家酒店，就可以通知酒店帮你找找看。</p>
<p><img src="https://wnnwoo.oss-cn-chengdu.aliyuncs.com/BluetoothLongRange/CommunityFound.png?x-oss-process=image/resize,p_50" alt></p>
</li>
<li><p><a href="https://www.apptricity.com/i-connect-ultra-long-range-bluetooth-beacon/">Apptricity</a>这家公司则号称可以让蓝牙传输距离增加到20迈（36公里），可是实在查不到到底是怎么做到的，在IEEE的一篇文章<a href="https://spectrum.ieee.org/tech-talk/telecom/wireless/apptricity-beams-bluetooth-signals-over-20-miles">Apptricity Beams Bluetooth Signals Over 30 Kilometers</a>很吝啬的提了一句说它们借助了激光的思想，怎么个借助法就再没提提了，最牛的是说他们在与军方的合作的非商业版里已经做到了80～120公里，天啊，这还是蓝牙吗，还有必要用蓝牙吗。</p>
<blockquote>
<p>The key new wrinkle, according to Apptricity’s CEO Tim Garcia, is precise tuning within the Bluetooth spectrum. Garcia says it’s the same principle as a tightly-focused laser beam. A laser beam will travel farther without its signal weakening beyond recovery if the photons making up the beam are all as close to a specific frequency as possible. Apptricity’s Bluetooth beacons use firmware developed by the company to achieve such precise tuning, but with Bluetooth signals instead of photons. Thus, data can be sent and received by the beacons without interfering and without requiring unwieldy amounts of power.<br><img src="https://wnnwoo.oss-cn-chengdu.aliyuncs.com/BluetoothLongRange/Bluetooth-20Miles.png?x-oss-process=image/resize,p_50" alt></p>
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            <p>看完下面这张图，你会发现你真正投入到工作上的时间在一辈子看来很少，所以你努力不了多少年，努力跟选择相比较，是选择更重要。<br><img src="https://wnnwoo.oss-cn-chengdu.aliyuncs.com/LifeCycleOfPeople/LifeCyclePeople.png" alt></p>

          
        
      
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            <p><a href="https://finance.sina.com.cn/china/gncj/2020-09-21/doc-iivhvpwy8038347.shtml">《中国大周期及其货币》（The Big Cycle of China and Its Currency）</a><br>中国重回巅峰时期，是新一轮的牛市。<br><img src="https://wnnwoo.oss-cn-chengdu.aliyuncs.com/RayDalio/WorrCountryTrend.png" alt></p>
<p>在过去的1400多年的大部分时间里，大多数朝代都非常强大，文明且繁荣。<br>　　唐朝以后，中国扩大了疆界，并经历了文化的繁荣。在南北朝时期（从900年代到1200年代），中国是世界上最具创新和活力的经济体。在明朝（1300到1600年代），中国是一个强大的大国，享有一段既富裕又和平的美好时期。在清朝初期（1600到1700年代），中国拥有最大的领土扩张范围，统治着世界三分之一的人口，同时拥有极其强大的经济实力。<br>　　然后在1800年代初期到1900年代上半年，中国实力衰落，而欧洲国家（尤其是大英帝国）实力增强。从1800年左右到最近，亚洲的财富和权力逐步转移到了欧洲，这是世界历史上最大一次的财富和权力转移，主要是由于中国的衰弱，这种权力和财富的转移应该认为这是一种反常现象，而不是常态。<br><img src="https://wnnwoo.oss-cn-chengdu.aliyuncs.com/RayDalio/RayDalioChinaDynasty.png" alt></p>

          
        
      
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            <p> 现在开始粉村上春树了，《海边的卡夫卡》中的一段关于命运的说辞：</p>
<blockquote>
<p> 某种情况下，命运这东西类似不断改变前进方向的局部沙尘暴。你变换脚步力图避开它，不料沙尘暴就像配合你似的同样变换脚步。你再次变换脚步，沙尘暴也变换脚步——如此无数次周而复始，恰如黎明前同死神一起跳的不吉利的舞。这是因为，沙尘暴不是来自远处什么地方的两不相关的什么。这是说，那家伙是你本身，是你本身中的什么。所以你能做的，不外乎乖乖地径直跨入那篇沙尘暴之中，紧紧捂住眼睛耳朵以免沙尘进入，一步一步从中穿过。那里面没有太阳，没有月亮，没有方向，有时甚至没有时间，唯有碎骨一样细细白白的沙尘在高空盘旋。<br>  而沙尘暴偃旗息鼓之时，你恐怕还不能完全明白自己是如何从中穿过而得以逃生的，甚至它是否已经远去你大概都无从判断。不过有一点是清楚的：从沙尘暴中逃出来的你已经不再是跨入沙尘暴时的你。这就是所谓沙尘暴的含义。</p>
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            <p><img src="https://wnnwoo.oss-cn-chengdu.aliyuncs.com/Logo/sweintooth_logo.jpg?x-oss-process=image/resize,p_50" alt><br>SweynTooth是新加坡科技设计大学（<a href="https://www.sutd.edu.sg">SUTD</a>）的一个<a href="https://asset-group.github.io">嵌入式设备安全研究机构</a>在今年2月释放出的10个针对BLE的攻击方法，这些攻击方法很常见，就是通过传输不符合规范的数据包，看被测设备会不会出现死锁或死机，相关的<a href="https://github.com/Matheus-Garbelini/sweyntooth_bluetooth_low_energy_attacks">攻击程序</a>也有开放。第二波的攻击方法将在7月13号发布。</p>
<p>关于为什么叫SweynTooth，很好玩，请参考下面一段。</p>
<blockquote>
<p>5 Why SweynTooth ?</p>
<p>The insight behind the name SweynTooth arrives from Sweyn Forkbeard, the son of King Harald Bluetooth (after whom the Bluetooth Technology was originally named). Sweyn revolted against Harald Bluetooth and this forced King Harald to his exile. The exile lead to the death of King Harald shortly. We envision that if SweynTooth style vulnerabilities are not appropriately handled by BLE vendors, then the technology can become a breeding ground for attackers. This may, in turn, lead the Bluetooth technology to be obsolete.</p>
</blockquote>
<p>斯文牙是蓝牙的儿子，斯文牙一点不斯文，他反叛父亲，并将父亲流放。鉴于此，SUTD发布这些无聊攻击也算是师出有名：为了不让蓝牙技术落到蓝牙的境地。原本的目的也许就是导师为了让学生有课题做作，好写毕业论文，你懂得。正常情况下谁有闲空去搞这些损人不利己的事儿呢？</p>
<p>比如其中的第二个攻击方法，就是将链路层数据包的LLID给写成0，而0在spec中规定是个没有意义的数字，在收到这样的数据包时应该直接丢弃。<br><img src="https://wnnwoo.oss-cn-chengdu.aliyuncs.com/Logo/SweynToothClearLLID.png" alt></p>
<p><img src="https://wnnwoo.oss-cn-chengdu.aliyuncs.com/Logo/DataChannelPDU-Header-LLID.png" alt></p>
<p>Nimble Controller在处理RX Data PDU的时候已经考虑到这个了，code如下。</p>
<figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br></pre></td><td class="code"><pre><span class="line">void</span><br><span class="line">ble_ll_conn_rx_data_pdu(struct os_mbuf *rxpdu, struct ble_mbuf_hdr *hdr)</span><br><span class="line">&#123;</span><br><span class="line">    /* Validate rx data pdu */</span><br><span class="line">    rxbuf = rxpdu-&gt;om_data;</span><br><span class="line">    hdr_byte = rxbuf[0];</span><br><span class="line">    acl_len = rxbuf[1];</span><br><span class="line">    llid = hdr_byte &amp; BLE_LL_DATA_HDR_LLID_MASK;</span><br><span class="line"></span><br><span class="line">    /*</span><br><span class="line">     * Check that the LLID and payload length are reasonable.</span><br><span class="line">     * Empty payload is only allowed for LLID == 01b.</span><br><span class="line">     *  */</span><br><span class="line">    if ((llid == 0) || ((acl_len == 0) &amp;&amp; (llid != BLE_LL_LLID_DATA_FRAG))) &#123;</span><br><span class="line">        STATS_INC(ble_ll_conn_stats, rx_bad_llid);</span><br><span class="line">        goto conn_rx_data_pdu_end;</span><br><span class="line">    &#125;</span><br></pre></td></tr></table></figure>

          
        
      
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            <p><a href="https://book.douban.com/subject/3910974/">QBQ</a>，一本小书，不到150页，一个小时读完。<br>一句话：这是一本老板喜欢的书，教员工要当责。<br>看书名，我被她深深的吸引了，这本书难道是关于逻辑学的？教你识别一个问题是不是一个问题，避免自己做无用功？然而我错了。<br>翻译下书名：提出带有负面情绪的问题，是有问题的。<br>全书的重点是在讲作为一个员工应该有的心态：做事当责，不抱怨，以正面心态拥抱当前的问题。当你改变到了这个心态，自己工作成效也大，进步也快。</p>

          
        
      
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